fs/btrfs/transaction.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/fs.h>
  20 #include <linux/slab.h>
  21 #include <linux/sched.h>
  22 #include <linux/writeback.h>
  23 #include <linux/pagemap.h>
  24 #include <linux/blkdev.h>
  25 #include <linux/uuid.h>
  26 #include "ctree.h"
  27 #include "disk-io.h"
  28 #include "transaction.h"
  29 #include "locking.h"
  30 #include "tree-log.h"
  31 #include "inode-map.h"
  32 #include "volumes.h"
  33 #include "dev-replace.h"
  34
  35 #define BTRFS_ROOT_TRANS_TAG 0
  36
  37 void put_transaction(struct btrfs_transaction *transaction)
  38 {
  39         WARN_ON(atomic_read(&transaction->use_count) == 0);
  40         if (atomic_dec_and_test(&transaction->use_count)) {
  41                 BUG_ON(!list_empty(&transaction->list));
  42                 WARN_ON(transaction->delayed_refs.root.rb_node);
  43                 kmem_cache_free(btrfs_transaction_cachep, transaction);
  44         }
  45 }
  46
  47 static noinline void switch_commit_root(struct btrfs_root *root)
  48 {
  49         free_extent_buffer(root->commit_root);
  50         root->commit_root = btrfs_root_node(root);
  51 }
  52
  53 static inline int can_join_transaction(struct btrfs_transaction *trans,
  54                                        int type)
  55 {
  56         return !(trans->in_commit &&
  57                  type != TRANS_JOIN &&
  58                  type != TRANS_JOIN_NOLOCK);
  59 }
  60
  61 /*
  62  * either allocate a new transaction or hop into the existing one
  63  */
  64 static noinline int join_transaction(struct btrfs_root *root, int type)
  65 {
  66         struct btrfs_transaction *cur_trans;
  67         struct btrfs_fs_info *fs_info = root->fs_info;
  68
  69         spin_lock(&fs_info->trans_lock);
  70 loop:
  71         /* The file system has been taken offline. No new transactions. */
  72         if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
  73                 spin_unlock(&fs_info->trans_lock);
  74                 return -EROFS;
  75         }
  76
  77         if (fs_info->trans_no_join) {
  78                 /*
  79                  * If we are JOIN_NOLOCK we're already committing a current
  80                  * transaction, we just need a handle to deal with something
  81                  * when committing the transaction, such as inode cache and
  82                  * space cache. It is a special case.
  83                  */
  84                 if (type != TRANS_JOIN_NOLOCK) {
  85                         spin_unlock(&fs_info->trans_lock);
  86                         return -EBUSY;
  87                 }
  88         }
  89
  90         cur_trans = fs_info->running_transaction;
  91         if (cur_trans) {
  92                 if (cur_trans->aborted) {
  93                         spin_unlock(&fs_info->trans_lock);
  94                         return cur_trans->aborted;
  95                 }
  96                 if (!can_join_transaction(cur_trans, type)) {
  97                         spin_unlock(&fs_info->trans_lock);
  98                         return -EBUSY;
  99                 }
 100                 atomic_inc(&cur_trans->use_count);
 101                 atomic_inc(&cur_trans->num_writers);
 102                 cur_trans->num_joined++;
 103                 spin_unlock(&fs_info->trans_lock);
 104                 return 0;
 105         }
 106         spin_unlock(&fs_info->trans_lock);
 107
 108         /*
 109          * If we are ATTACH, we just want to catch the current transaction,
 110          * and commit it. If there is no transaction, just return ENOENT.
 111          */
 112         if (type == TRANS_ATTACH)
 113                 return -ENOENT;
 114
 115         cur_trans = kmem_cache_alloc(btrfs_transaction_cachep, GFP_NOFS);
 116         if (!cur_trans)
 117                 return -ENOMEM;
 118
 119         spin_lock(&fs_info->trans_lock);
 120         if (fs_info->running_transaction) {
 121                 /*
 122                  * someone started a transaction after we unlocked.  Make sure
 123                  * to redo the trans_no_join checks above
 124                  */
 125                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 126                 goto loop;
 127         } else if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
 128                 spin_unlock(&fs_info->trans_lock);
 129                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 130                 return -EROFS;
 131         }
 132
 133         atomic_set(&cur_trans->num_writers, 1);
 134         cur_trans->num_joined = 0;
 135         init_waitqueue_head(&cur_trans->writer_wait);
 136         init_waitqueue_head(&cur_trans->commit_wait);
 137         cur_trans->in_commit = 0;
 138         cur_trans->blocked = 0;
 139         /*
 140          * One for this trans handle, one so it will live on until we
 141          * commit the transaction.
 142          */
 143         atomic_set(&cur_trans->use_count, 2);
 144         cur_trans->commit_done = 0;
 145         cur_trans->start_time = get_seconds();
 146
 147         cur_trans->delayed_refs.root = RB_ROOT;
 148         cur_trans->delayed_refs.num_entries = 0;
 149         cur_trans->delayed_refs.num_heads_ready = 0;
 150         cur_trans->delayed_refs.num_heads = 0;
 151         cur_trans->delayed_refs.flushing = 0;
 152         cur_trans->delayed_refs.run_delayed_start = 0;
 153
 154         /*
 155          * although the tree mod log is per file system and not per transaction,
 156          * the log must never go across transaction boundaries.
 157          */
 158         smp_mb();
 159         if (!list_empty(&fs_info->tree_mod_seq_list))
 160                 WARN(1, KERN_ERR "btrfs: tree_mod_seq_list not empty when "
 161                         "creating a fresh transaction\n");
 162         if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log))
 163                 WARN(1, KERN_ERR "btrfs: tree_mod_log rb tree not empty when "
 164                         "creating a fresh transaction\n");
 165         atomic_set(&fs_info->tree_mod_seq, 0);
 166
 167         spin_lock_init(&cur_trans->commit_lock);
 168         spin_lock_init(&cur_trans->delayed_refs.lock);
 169         atomic_set(&cur_trans->delayed_refs.procs_running_refs, 0);
 170         atomic_set(&cur_trans->delayed_refs.ref_seq, 0);
 171         init_waitqueue_head(&cur_trans->delayed_refs.wait);
 172
 173         INIT_LIST_HEAD(&cur_trans->pending_snapshots);
 174         INIT_LIST_HEAD(&cur_trans->ordered_operations);
 175         list_add_tail(&cur_trans->list, &fs_info->trans_list);
 176         extent_io_tree_init(&cur_trans->dirty_pages,
 177                              fs_info->btree_inode->i_mapping);
 178         fs_info->generation++;
 179         cur_trans->transid = fs_info->generation;
 180         fs_info->running_transaction = cur_trans;
 181         cur_trans->aborted = 0;
 182         spin_unlock(&fs_info->trans_lock);
 183
 184         return 0;
 185 }
 186
 187 /*
 188  * this does all the record keeping required to make sure that a reference
 189  * counted root is properly recorded in a given transaction.  This is required
 190  * to make sure the old root from before we joined the transaction is deleted
 191  * when the transaction commits
 192  */
 193 static int record_root_in_trans(struct btrfs_trans_handle *trans,
 194                                struct btrfs_root *root)
 195 {
 196         if (root->ref_cows && root->last_trans < trans->transid) {
 197                 WARN_ON(root == root->fs_info->extent_root);
 198                 WARN_ON(root->commit_root != root->node);
 199
 200                 /*
 201                  * see below for in_trans_setup usage rules
 202                  * we have the reloc mutex held now, so there
 203                  * is only one writer in this function
 204                  */
 205                 root->in_trans_setup = 1;
 206
 207                 /* make sure readers find in_trans_setup before
 208                  * they find our root->last_trans update
 209                  */
 210                 smp_wmb();
 211
 212                 spin_lock(&root->fs_info->fs_roots_radix_lock);
 213                 if (root->last_trans == trans->transid) {
 214                         spin_unlock(&root->fs_info->fs_roots_radix_lock);
 215                         return 0;
 216                 }
 217                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
 218                            (unsigned long)root->root_key.objectid,
 219                            BTRFS_ROOT_TRANS_TAG);
 220                 spin_unlock(&root->fs_info->fs_roots_radix_lock);
 221                 root->last_trans = trans->transid;
 222
 223                 /* this is pretty tricky.  We don't want to
 224                  * take the relocation lock in btrfs_record_root_in_trans
 225                  * unless we're really doing the first setup for this root in
 226                  * this transaction.
 227                  *
 228                  * Normally we'd use root->last_trans as a flag to decide
 229                  * if we want to take the expensive mutex.
 230                  *
 231                  * But, we have to set root->last_trans before we
 232                  * init the relocation root, otherwise, we trip over warnings
 233                  * in ctree.c.  The solution used here is to flag ourselves
 234                  * with root->in_trans_setup.  When this is 1, we're still
 235                  * fixing up the reloc trees and everyone must wait.
 236                  *
 237                  * When this is zero, they can trust root->last_trans and fly
 238                  * through btrfs_record_root_in_trans without having to take the
 239                  * lock.  smp_wmb() makes sure that all the writes above are
 240                  * done before we pop in the zero below
 241                  */
 242                 btrfs_init_reloc_root(trans, root);
 243                 smp_wmb();
 244                 root->in_trans_setup = 0;
 245         }
 246         return 0;
 247 }
 248
 249
 250 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 251                                struct btrfs_root *root)
 252 {
 253         if (!root->ref_cows)
 254                 return 0;
 255
 256         /*
 257          * see record_root_in_trans for comments about in_trans_setup usage
 258          * and barriers
 259          */
 260         smp_rmb();
 261         if (root->last_trans == trans->transid &&
 262             !root->in_trans_setup)
 263                 return 0;
 264
 265         mutex_lock(&root->fs_info->reloc_mutex);
 266         record_root_in_trans(trans, root);
 267         mutex_unlock(&root->fs_info->reloc_mutex);
 268
 269         return 0;
 270 }
 271
 272 /* wait for commit against the current transaction to become unblocked
 273  * when this is done, it is safe to start a new transaction, but the current
 274  * transaction might not be fully on disk.
 275  */
 276 static void wait_current_trans(struct btrfs_root *root)
 277 {
 278         struct btrfs_transaction *cur_trans;
 279
 280         spin_lock(&root->fs_info->trans_lock);
 281         cur_trans = root->fs_info->running_transaction;
 282         if (cur_trans && cur_trans->blocked) {
 283                 atomic_inc(&cur_trans->use_count);
 284                 spin_unlock(&root->fs_info->trans_lock);
 285
 286                 wait_event(root->fs_info->transaction_wait,
 287                            !cur_trans->blocked);
 288                 put_transaction(cur_trans);
 289         } else {
 290                 spin_unlock(&root->fs_info->trans_lock);
 291         }
 292 }
 293
 294 static int may_wait_transaction(struct btrfs_root *root, int type)
 295 {
 296         if (root->fs_info->log_root_recovering)
 297                 return 0;
 298
 299         if (type == TRANS_USERSPACE)
 300                 return 1;
 301
 302         if (type == TRANS_START &&
 303             !atomic_read(&root->fs_info->open_ioctl_trans))
 304                 return 1;
 305
 306         return 0;
 307 }
 308
 309 static struct btrfs_trans_handle *
 310 start_transaction(struct btrfs_root *root, u64 num_items, int type,
 311                   enum btrfs_reserve_flush_enum flush)
 312 {
 313         struct btrfs_trans_handle *h;
 314         struct btrfs_transaction *cur_trans;
 315         u64 num_bytes = 0;
 316         int ret;
 317         u64 qgroup_reserved = 0;
 318
 319         if (test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state))
 320                 return ERR_PTR(-EROFS);
 321
 322         if (current->journal_info) {
 323                 WARN_ON(type != TRANS_JOIN && type != TRANS_JOIN_NOLOCK);
 324                 h = current->journal_info;
 325                 h->use_count++;
 326                 WARN_ON(h->use_count > 2);
 327                 h->orig_rsv = h->block_rsv;
 328                 h->block_rsv = NULL;
 329                 goto got_it;
 330         }
 331
 332         /*
 333          * Do the reservation before we join the transaction so we can do all
 334          * the appropriate flushing if need be.
 335          */
 336         if (num_items > 0 && root != root->fs_info->chunk_root) {
 337                 if (root->fs_info->quota_enabled &&
 338                     is_fstree(root->root_key.objectid)) {
 339                         qgroup_reserved = num_items * root->leafsize;
 340                         ret = btrfs_qgroup_reserve(root, qgroup_reserved);
 341                         if (ret)
 342                                 return ERR_PTR(ret);
 343                 }
 344
 345                 num_bytes = btrfs_calc_trans_metadata_size(root, num_items);
 346                 ret = btrfs_block_rsv_add(root,
 347                                           &root->fs_info->trans_block_rsv,
 348                                           num_bytes, flush);
 349                 if (ret)
 350                         goto reserve_fail;
 351         }
 352 again:
 353         h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 354         if (!h) {
 355                 ret = -ENOMEM;
 356                 goto alloc_fail;
 357         }
 358
 359         /*
 360          * If we are JOIN_NOLOCK we're already committing a transaction and
 361          * waiting on this guy, so we don't need to do the sb_start_intwrite
 362          * because we're already holding a ref.  We need this because we could
 363          * have raced in and did an fsync() on a file which can kick a commit
 364          * and then we deadlock with somebody doing a freeze.
 365          *
 366          * If we are ATTACH, it means we just want to catch the current
 367          * transaction and commit it, so we needn't do sb_start_intwrite().
 368          */
 369         if (type < TRANS_JOIN_NOLOCK)
 370                 sb_start_intwrite(root->fs_info->sb);
 371
 372         if (may_wait_transaction(root, type))
 373                 wait_current_trans(root);
 374
 375         do {
 376                 ret = join_transaction(root, type);
 377                 if (ret == -EBUSY) {
 378                         wait_current_trans(root);
 379                         if (unlikely(type == TRANS_ATTACH))
 380                                 ret = -ENOENT;
 381                 }
 382         } while (ret == -EBUSY);
 383
 384         if (ret < 0) {
 385                 /* We must get the transaction if we are JOIN_NOLOCK. */
 386                 BUG_ON(type == TRANS_JOIN_NOLOCK);
 387                 goto join_fail;
 388         }
 389
 390         cur_trans = root->fs_info->running_transaction;
 391
 392         h->transid = cur_trans->transid;
 393         h->transaction = cur_trans;
 394         h->blocks_used = 0;
 395         h->bytes_reserved = 0;
 396         h->root = root;
 397         h->delayed_ref_updates = 0;
 398         h->use_count = 1;
 399         h->adding_csums = 0;
 400         h->block_rsv = NULL;
 401         h->orig_rsv = NULL;
 402         h->aborted = 0;
 403         h->qgroup_reserved = 0;
 404         h->delayed_ref_elem.seq = 0;
 405         h->type = type;
 406         h->allocating_chunk = false;
 407         INIT_LIST_HEAD(&h->qgroup_ref_list);
 408         INIT_LIST_HEAD(&h->new_bgs);
 409
 410         smp_mb();
 411         if (cur_trans->blocked && may_wait_transaction(root, type)) {
 412                 btrfs_commit_transaction(h, root);
 413                 goto again;
 414         }
 415
 416         if (num_bytes) {
 417                 trace_btrfs_space_reservation(root->fs_info, "transaction",
 418                                               h->transid, num_bytes, 1);
 419                 h->block_rsv = &root->fs_info->trans_block_rsv;
 420                 h->bytes_reserved = num_bytes;
 421         }
 422         h->qgroup_reserved = qgroup_reserved;
 423
 424 got_it:
 425         btrfs_record_root_in_trans(h, root);
 426
 427         if (!current->journal_info && type != TRANS_USERSPACE)
 428                 current->journal_info = h;
 429         return h;
 430
 431 join_fail:
 432         if (type < TRANS_JOIN_NOLOCK)
 433                 sb_end_intwrite(root->fs_info->sb);
 434         kmem_cache_free(btrfs_trans_handle_cachep, h);
 435 alloc_fail:
 436         if (num_bytes)
 437                 btrfs_block_rsv_release(root, &root->fs_info->trans_block_rsv,
 438                                         num_bytes);
 439 reserve_fail:
 440         if (qgroup_reserved)
 441                 btrfs_qgroup_free(root, qgroup_reserved);
 442         return ERR_PTR(ret);
 443 }
 444
 445 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 446                                                    int num_items)
 447 {
 448         return start_transaction(root, num_items, TRANS_START,
 449                                  BTRFS_RESERVE_FLUSH_ALL);
 450 }
 451
 452 struct btrfs_trans_handle *btrfs_start_transaction_lflush(
 453                                         struct btrfs_root *root, int num_items)
 454 {
 455         return start_transaction(root, num_items, TRANS_START,
 456                                  BTRFS_RESERVE_FLUSH_LIMIT);
 457 }
 458
 459 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
 460 {
 461         return start_transaction(root, 0, TRANS_JOIN, 0);
 462 }
 463
 464 struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root)
 465 {
 466         return start_transaction(root, 0, TRANS_JOIN_NOLOCK, 0);
 467 }
 468
 469 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root)
 470 {
 471         return start_transaction(root, 0, TRANS_USERSPACE, 0);
 472 }
 473
 474 /*
 475  * btrfs_attach_transaction() - catch the running transaction
 476  *
 477  * It is used when we want to commit the current the transaction, but
 478  * don't want to start a new one.
 479  *
 480  * Note: If this function return -ENOENT, it just means there is no
 481  * running transaction. But it is possible that the inactive transaction
 482  * is still in the memory, not fully on disk. If you hope there is no
 483  * inactive transaction in the fs when -ENOENT is returned, you should
 484  * invoke
 485  *     btrfs_attach_transaction_barrier()
 486  */
 487 struct btrfs_trans_handle *btrfs_attach_transaction(struct btrfs_root *root)
 488 {
 489         return start_transaction(root, 0, TRANS_ATTACH, 0);
 490 }
 491
 492 /*
 493  * btrfs_attach_transaction() - catch the running transaction
 494  *
 495  * It is similar to the above function, the differentia is this one
 496  * will wait for all the inactive transactions until they fully
 497  * complete.
 498  */
 499 struct btrfs_trans_handle *
 500 btrfs_attach_transaction_barrier(struct btrfs_root *root)
 501 {
 502         struct btrfs_trans_handle *trans;
 503
 504         trans = start_transaction(root, 0, TRANS_ATTACH, 0);
 505         if (IS_ERR(trans) && PTR_ERR(trans) == -ENOENT)
 506                 btrfs_wait_for_commit(root, 0);
 507
 508         return trans;
 509 }
 510
 511 /* wait for a transaction commit to be fully complete */
 512 static noinline void wait_for_commit(struct btrfs_root *root,
 513                                     struct btrfs_transaction *commit)
 514 {
 515         wait_event(commit->commit_wait, commit->commit_done);
 516 }
 517
 518 int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
 519 {
 520         struct btrfs_transaction *cur_trans = NULL, *t;
 521         int ret = 0;
 522
 523         if (transid) {
 524                 if (transid <= root->fs_info->last_trans_committed)
 525                         goto out;
 526
 527                 ret = -EINVAL;
 528                 /* find specified transaction */
 529                 spin_lock(&root->fs_info->trans_lock);
 530                 list_for_each_entry(t, &root->fs_info->trans_list, list) {
 531                         if (t->transid == transid) {
 532                                 cur_trans = t;
 533                                 atomic_inc(&cur_trans->use_count);
 534                                 ret = 0;
 535                                 break;
 536                         }
 537                         if (t->transid > transid) {
 538                                 ret = 0;
 539                                 break;
 540                         }
 541                 }
 542                 spin_unlock(&root->fs_info->trans_lock);
 543                 /* The specified transaction doesn't exist */
 544                 if (!cur_trans)
 545                         goto out;
 546         } else {
 547                 /* find newest transaction that is committing | committed */
 548                 spin_lock(&root->fs_info->trans_lock);
 549                 list_for_each_entry_reverse(t, &root->fs_info->trans_list,
 550                                             list) {
 551                         if (t->in_commit) {
 552                                 if (t->commit_done)
 553                                         break;
 554                                 cur_trans = t;
 555                                 atomic_inc(&cur_trans->use_count);
 556                                 break;
 557                         }
 558                 }
 559                 spin_unlock(&root->fs_info->trans_lock);
 560                 if (!cur_trans)
 561                         goto out;  /* nothing committing|committed */
 562         }
 563
 564         wait_for_commit(root, cur_trans);
 565         put_transaction(cur_trans);
 566 out:
 567         return ret;
 568 }
 569
 570 void btrfs_throttle(struct btrfs_root *root)
 571 {
 572         if (!atomic_read(&root->fs_info->open_ioctl_trans))
 573                 wait_current_trans(root);
 574 }
 575
 576 static int should_end_transaction(struct btrfs_trans_handle *trans,
 577                                   struct btrfs_root *root)
 578 {
 579         int ret;
 580
 581         ret = btrfs_block_rsv_check(root, &root->fs_info->global_block_rsv, 5);
 582         return ret ? 1 : 0;
 583 }
 584
 585 int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
 586                                  struct btrfs_root *root)
 587 {
 588         struct btrfs_transaction *cur_trans = trans->transaction;
 589         int updates;
 590         int err;
 591
 592         smp_mb();
 593         if (cur_trans->blocked || cur_trans->delayed_refs.flushing)
 594                 return 1;
 595
 596         updates = trans->delayed_ref_updates;
 597         trans->delayed_ref_updates = 0;
 598         if (updates) {
 599                 err = btrfs_run_delayed_refs(trans, root, updates);
 600                 if (err) /* Error code will also eval true */
 601                         return err;
 602         }
 603
 604         return should_end_transaction(trans, root);
 605 }
 606
 607 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 608                           struct btrfs_root *root, int throttle)
 609 {
 610         struct btrfs_transaction *cur_trans = trans->transaction;
 611         struct btrfs_fs_info *info = root->fs_info;
 612         int count = 0;
 613         int lock = (trans->type != TRANS_JOIN_NOLOCK);
 614         int err = 0;
 615
 616         if (--trans->use_count) {
 617                 trans->block_rsv = trans->orig_rsv;
 618                 return 0;
 619         }
 620
 621         /*
 622          * do the qgroup accounting as early as possible
 623          */
 624         err = btrfs_delayed_refs_qgroup_accounting(trans, info);
 625
 626         btrfs_trans_release_metadata(trans, root);
 627         trans->block_rsv = NULL;
 628
 629         if (trans->qgroup_reserved) {
 630                 /*
 631                  * the same root has to be passed here between start_transaction
 632                  * and end_transaction. Subvolume quota depends on this.
 633                  */
 634                 btrfs_qgroup_free(trans->root, trans->qgroup_reserved);
 635                 trans->qgroup_reserved = 0;
 636         }
 637
 638         if (!list_empty(&trans->new_bgs))
 639                 btrfs_create_pending_block_groups(trans, root);
 640
 641         while (count < 1) {
 642                 unsigned long cur = trans->delayed_ref_updates;
 643                 trans->delayed_ref_updates = 0;
 644                 if (cur &&
 645                     trans->transaction->delayed_refs.num_heads_ready > 64) {
 646                         trans->delayed_ref_updates = 0;
 647                         btrfs_run_delayed_refs(trans, root, cur);
 648                 } else {
 649                         break;
 650                 }
 651                 count++;
 652         }
 653
 654         btrfs_trans_release_metadata(trans, root);
 655         trans->block_rsv = NULL;
 656
 657         if (!list_empty(&trans->new_bgs))
 658                 btrfs_create_pending_block_groups(trans, root);
 659
 660         if (lock && !atomic_read(&root->fs_info->open_ioctl_trans) &&
 661             should_end_transaction(trans, root)) {
 662                 trans->transaction->blocked = 1;
 663                 smp_wmb();
 664         }
 665
 666         if (lock && cur_trans->blocked && !cur_trans->in_commit) {
 667                 if (throttle) {
 668                         /*
 669                          * We may race with somebody else here so end up having
 670                          * to call end_transaction on ourselves again, so inc
 671                          * our use_count.
 672                          */
 673                         trans->use_count++;
 674                         return btrfs_commit_transaction(trans, root);
 675                 } else {
 676                         wake_up_process(info->transaction_kthread);
 677                 }
 678         }
 679
 680         if (trans->type < TRANS_JOIN_NOLOCK)
 681                 sb_end_intwrite(root->fs_info->sb);
 682
 683         WARN_ON(cur_trans != info->running_transaction);
 684         WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
 685         atomic_dec(&cur_trans->num_writers);
 686
 687         smp_mb();
 688         if (waitqueue_active(&cur_trans->writer_wait))
 689                 wake_up(&cur_trans->writer_wait);
 690         put_transaction(cur_trans);
 691
 692         if (current->journal_info == trans)
 693                 current->journal_info = NULL;
 694
 695         if (throttle)
 696                 btrfs_run_delayed_iputs(root);
 697
 698         if (trans->aborted ||
 699             test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state))
 700                 err = -EIO;
 701         assert_qgroups_uptodate(trans);
 702
 703         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 704         return err;
 705 }
 706
 707 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 708                           struct btrfs_root *root)
 709 {
 710         int ret;
 711
 712         ret = __btrfs_end_transaction(trans, root, 0);
 713         if (ret)
 714                 return ret;
 715         return 0;
 716 }
 717
 718 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 719                                    struct btrfs_root *root)
 720 {
 721         int ret;
 722
 723         ret = __btrfs_end_transaction(trans, root, 1);
 724         if (ret)
 725                 return ret;
 726         return 0;
 727 }
 728
 729 int btrfs_end_transaction_dmeta(struct btrfs_trans_handle *trans,
 730                                 struct btrfs_root *root)
 731 {
 732         return __btrfs_end_transaction(trans, root, 1);
 733 }
 734
 735 /*
 736  * when btree blocks are allocated, they have some corresponding bits set for
 737  * them in one of two extent_io trees.  This is used to make sure all of
 738  * those extents are sent to disk but does not wait on them
 739  */
 740 int btrfs_write_marked_extents(struct btrfs_root *root,
 741                                struct extent_io_tree *dirty_pages, int mark)
 742 {
 743         int err = 0;
 744         int werr = 0;
 745         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 746         struct extent_state *cached_state = NULL;
 747         u64 start = 0;
 748         u64 end;
 749         struct blk_plug plug;
 750
 751         blk_start_plug(&plug);
 752         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 753                                       mark, &cached_state)) {
 754                 convert_extent_bit(dirty_pages, start, end, EXTENT_NEED_WAIT,
 755                                    mark, &cached_state, GFP_NOFS);
 756                 cached_state = NULL;
 757                 err = filemap_fdatawrite_range(mapping, start, end);
 758                 if (err)
 759                         werr = err;
 760                 cond_resched();
 761                 start = end + 1;
 762         }
 763         if (err)
 764                 werr = err;
 765         blk_finish_plug(&plug);
 766         return werr;
 767 }
 768
 769 /*
 770  * when btree blocks are allocated, they have some corresponding bits set for
 771  * them in one of two extent_io trees.  This is used to make sure all of
 772  * those extents are on disk for transaction or log commit.  We wait
 773  * on all the pages and clear them from the dirty pages state tree
 774  */
 775 int btrfs_wait_marked_extents(struct btrfs_root *root,
 776                               struct extent_io_tree *dirty_pages, int mark)
 777 {
 778         int err = 0;
 779         int werr = 0;
 780         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 781         struct extent_state *cached_state = NULL;
 782         u64 start = 0;
 783         u64 end;
 784
 785         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 786                                       EXTENT_NEED_WAIT, &cached_state)) {
 787                 clear_extent_bit(dirty_pages, start, end, EXTENT_NEED_WAIT,
 788                                  0, 0, &cached_state, GFP_NOFS);
 789                 err = filemap_fdatawait_range(mapping, start, end);
 790                 if (err)
 791                         werr = err;
 792                 cond_resched();
 793                 start = end + 1;
 794         }
 795         if (err)
 796                 werr = err;
 797         return werr;
 798 }
 799
 800 /*
 801  * when btree blocks are allocated, they have some corresponding bits set for
 802  * them in one of two extent_io trees.  This is used to make sure all of
 803  * those extents are on disk for transaction or log commit
 804  */
 805 int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
 806                                 struct extent_io_tree *dirty_pages, int mark)
 807 {
 808         int ret;
 809         int ret2;
 810
 811         ret = btrfs_write_marked_extents(root, dirty_pages, mark);
 812         ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark);
 813
 814         if (ret)
 815                 return ret;
 816         if (ret2)
 817                 return ret2;
 818         return 0;
 819 }
 820
 821 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 822                                      struct btrfs_root *root)
 823 {
 824         if (!trans || !trans->transaction) {
 825                 struct inode *btree_inode;
 826                 btree_inode = root->fs_info->btree_inode;
 827                 return filemap_write_and_wait(btree_inode->i_mapping);
 828         }
 829         return btrfs_write_and_wait_marked_extents(root,
 830                                            &trans->transaction->dirty_pages,
 831                                            EXTENT_DIRTY);
 832 }
 833
 834 /*
 835  * this is used to update the root pointer in the tree of tree roots.
 836  *
 837  * But, in the case of the extent allocation tree, updating the root
 838  * pointer may allocate blocks which may change the root of the extent
 839  * allocation tree.
 840  *
 841  * So, this loops and repeats and makes sure the cowonly root didn't
 842  * change while the root pointer was being updated in the metadata.
 843  */
 844 static int update_cowonly_root(struct btrfs_trans_handle *trans,
 845                                struct btrfs_root *root)
 846 {
 847         int ret;
 848         u64 old_root_bytenr;
 849         u64 old_root_used;
 850         struct btrfs_root *tree_root = root->fs_info->tree_root;
 851
 852         old_root_used = btrfs_root_used(&root->root_item);
 853         btrfs_write_dirty_block_groups(trans, root);
 854
 855         while (1) {
 856                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
 857                 if (old_root_bytenr == root->node->start &&
 858                     old_root_used == btrfs_root_used(&root->root_item))
 859                         break;
 860
 861                 btrfs_set_root_node(&root->root_item, root->node);
 862                 ret = btrfs_update_root(trans, tree_root,
 863                                         &root->root_key,
 864                                         &root->root_item);
 865                 if (ret)
 866                         return ret;
 867
 868                 old_root_used = btrfs_root_used(&root->root_item);
 869                 ret = btrfs_write_dirty_block_groups(trans, root);
 870                 if (ret)
 871                         return ret;
 872         }
 873
 874         if (root != root->fs_info->extent_root)
 875                 switch_commit_root(root);
 876
 877         return 0;
 878 }
 879
 880 /*
 881  * update all the cowonly tree roots on disk
 882  *
 883  * The error handling in this function may not be obvious. Any of the
 884  * failures will cause the file system to go offline. We still need
 885  * to clean up the delayed refs.
 886  */
 887 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
 888                                          struct btrfs_root *root)
 889 {
 890         struct btrfs_fs_info *fs_info = root->fs_info;
 891         struct list_head *next;
 892         struct extent_buffer *eb;
 893         int ret;
 894
 895         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 896         if (ret)
 897                 return ret;
 898
 899         eb = btrfs_lock_root_node(fs_info->tree_root);
 900         ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL,
 901                               0, &eb);
 902         btrfs_tree_unlock(eb);
 903         free_extent_buffer(eb);
 904
 905         if (ret)
 906                 return ret;
 907
 908         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 909         if (ret)
 910                 return ret;
 911
 912         ret = btrfs_run_dev_stats(trans, root->fs_info);
 913         WARN_ON(ret);
 914         ret = btrfs_run_dev_replace(trans, root->fs_info);
 915         WARN_ON(ret);
 916
 917         ret = btrfs_run_qgroups(trans, root->fs_info);
 918         BUG_ON(ret);
 919
 920         /* run_qgroups might have added some more refs */
 921         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 922         BUG_ON(ret);
 923
 924         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
 925                 next = fs_info->dirty_cowonly_roots.next;
 926                 list_del_init(next);
 927                 root = list_entry(next, struct btrfs_root, dirty_list);
 928
 929                 ret = update_cowonly_root(trans, root);
 930                 if (ret)
 931                         return ret;
 932         }
 933
 934         down_write(&fs_info->extent_commit_sem);
 935         switch_commit_root(fs_info->extent_root);
 936         up_write(&fs_info->extent_commit_sem);
 937
 938         btrfs_after_dev_replace_commit(fs_info);
 939
 940         return 0;
 941 }
 942
 943 /*
 944  * dead roots are old snapshots that need to be deleted.  This allocates
 945  * a dirty root struct and adds it into the list of dead roots that need to
 946  * be deleted
 947  */
 948 int btrfs_add_dead_root(struct btrfs_root *root)
 949 {
 950         spin_lock(&root->fs_info->trans_lock);
 951         list_add_tail(&root->root_list, &root->fs_info->dead_roots);
 952         spin_unlock(&root->fs_info->trans_lock);
 953         return 0;
 954 }
 955
 956 /*
 957  * update all the cowonly tree roots on disk
 958  */
 959 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
 960                                     struct btrfs_root *root)
 961 {
 962         struct btrfs_root *gang[8];
 963         struct btrfs_fs_info *fs_info = root->fs_info;
 964         int i;
 965         int ret;
 966         int err = 0;
 967
 968         spin_lock(&fs_info->fs_roots_radix_lock);
 969         while (1) {
 970                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
 971                                                  (void **)gang, 0,
 972                                                  ARRAY_SIZE(gang),
 973                                                  BTRFS_ROOT_TRANS_TAG);
 974                 if (ret == 0)
 975                         break;
 976                 for (i = 0; i < ret; i++) {
 977                         root = gang[i];
 978                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
 979                                         (unsigned long)root->root_key.objectid,
 980                                         BTRFS_ROOT_TRANS_TAG);
 981                         spin_unlock(&fs_info->fs_roots_radix_lock);
 982
 983                         btrfs_free_log(trans, root);
 984                         btrfs_update_reloc_root(trans, root);
 985                         btrfs_orphan_commit_root(trans, root);
 986
 987                         btrfs_save_ino_cache(root, trans);
 988
 989                         /* see comments in should_cow_block() */
 990                         root->force_cow = 0;
 991                         smp_wmb();
 992
 993                         if (root->commit_root != root->node) {
 994                                 mutex_lock(&root->fs_commit_mutex);
 995                                 switch_commit_root(root);
 996                                 btrfs_unpin_free_ino(root);
 997                                 mutex_unlock(&root->fs_commit_mutex);
 998
 999                                 btrfs_set_root_node(&root->root_item,
1000                                                     root->node);
1001                         }
1002
1003                         err = btrfs_update_root(trans, fs_info->tree_root,
1004                                                 &root->root_key,
1005                                                 &root->root_item);
1006                         spin_lock(&fs_info->fs_roots_radix_lock);
1007                         if (err)
1008                                 break;
1009                 }
1010         }
1011         spin_unlock(&fs_info->fs_roots_radix_lock);
1012         return err;
1013 }
1014
1015 /*
1016  * defrag a given btree.
1017  * Every leaf in the btree is read and defragged.
1018  */
1019 int btrfs_defrag_root(struct btrfs_root *root)
1020 {
1021         struct btrfs_fs_info *info = root->fs_info;
1022         struct btrfs_trans_handle *trans;
1023         int ret;
1024
1025         if (xchg(&root->defrag_running, 1))
1026                 return 0;
1027
1028         while (1) {
1029                 trans = btrfs_start_transaction(root, 0);
1030                 if (IS_ERR(trans))
1031                         return PTR_ERR(trans);
1032
1033                 ret = btrfs_defrag_leaves(trans, root);
1034
1035                 btrfs_end_transaction(trans, root);
1036                 btrfs_btree_balance_dirty(info->tree_root);
1037                 cond_resched();
1038
1039                 if (btrfs_fs_closing(root->fs_info) || ret != -EAGAIN)
1040                         break;
1041
1042                 if (btrfs_defrag_cancelled(root->fs_info)) {
1043                         printk(KERN_DEBUG "btrfs: defrag_root cancelled\n");
1044                         ret = -EAGAIN;
1045                         break;
1046                 }
1047         }
1048         root->defrag_running = 0;
1049         return ret;
1050 }
1051
1052 /*
1053  * new snapshots need to be created at a very specific time in the
1054  * transaction commit.  This does the actual creation.
1055  *
1056  * Note:
1057  * If the error which may affect the commitment of the current transaction
1058  * happens, we should return the error number. If the error which just affect
1059  * the creation of the pending snapshots, just return 0.
1060  */
1061 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
1062                                    struct btrfs_fs_info *fs_info,
1063                                    struct btrfs_pending_snapshot *pending)
1064 {
1065         struct btrfs_key key;
1066         struct btrfs_root_item *new_root_item;
1067         struct btrfs_root *tree_root = fs_info->tree_root;
1068         struct btrfs_root *root = pending->root;
1069         struct btrfs_root *parent_root;
1070         struct btrfs_block_rsv *rsv;
1071         struct inode *parent_inode;
1072         struct btrfs_path *path;
1073         struct btrfs_dir_item *dir_item;
1074         struct dentry *dentry;
1075         struct extent_buffer *tmp;
1076         struct extent_buffer *old;
1077         struct timespec cur_time = CURRENT_TIME;
1078         int ret = 0;
1079         u64 to_reserve = 0;
1080         u64 index = 0;
1081         u64 objectid;
1082         u64 root_flags;
1083         uuid_le new_uuid;
1084
1085         path = btrfs_alloc_path();
1086         if (!path) {
1087                 pending->error = -ENOMEM;
1088                 return 0;
1089         }
1090
1091         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
1092         if (!new_root_item) {
1093                 pending->error = -ENOMEM;
1094                 goto root_item_alloc_fail;
1095         }
1096
1097         pending->error = btrfs_find_free_objectid(tree_root, &objectid);
1098         if (pending->error)
1099                 goto no_free_objectid;
1100
1101         btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
1102
1103         if (to_reserve > 0) {
1104                 pending->error = btrfs_block_rsv_add(root,
1105                                                      &pending->block_rsv,
1106                                                      to_reserve,
1107                                                      BTRFS_RESERVE_NO_FLUSH);
1108                 if (pending->error)
1109                         goto no_free_objectid;
1110         }
1111
1112         pending->error = btrfs_qgroup_inherit(trans, fs_info,
1113                                               root->root_key.objectid,
1114                                               objectid, pending->inherit);
1115         if (pending->error)
1116                 goto no_free_objectid;
1117
1118         key.objectid = objectid;
1119         key.offset = (u64)-1;
1120         key.type = BTRFS_ROOT_ITEM_KEY;
1121
1122         rsv = trans->block_rsv;
1123         trans->block_rsv = &pending->block_rsv;
1124         trans->bytes_reserved = trans->block_rsv->reserved;
1125
1126         dentry = pending->dentry;
1127         parent_inode = pending->dir;
1128         parent_root = BTRFS_I(parent_inode)->root;
1129         record_root_in_trans(trans, parent_root);
1130
1131         /*
1132          * insert the directory item
1133          */
1134         ret = btrfs_set_inode_index(parent_inode, &index);
1135         BUG_ON(ret); /* -ENOMEM */
1136
1137         /* check if there is a file/dir which has the same name. */
1138         dir_item = btrfs_lookup_dir_item(NULL, parent_root, path,
1139                                          btrfs_ino(parent_inode),
1140                                          dentry->d_name.name,
1141                                          dentry->d_name.len, 0);
1142         if (dir_item != NULL && !IS_ERR(dir_item)) {
1143                 pending->error = -EEXIST;
1144                 goto dir_item_existed;
1145         } else if (IS_ERR(dir_item)) {
1146                 ret = PTR_ERR(dir_item);
1147                 btrfs_abort_transaction(trans, root, ret);
1148                 goto fail;
1149         }
1150         btrfs_release_path(path);
1151
1152         /*
1153          * pull in the delayed directory update
1154          * and the delayed inode item
1155          * otherwise we corrupt the FS during
1156          * snapshot
1157          */
1158         ret = btrfs_run_delayed_items(trans, root);
1159         if (ret) {      /* Transaction aborted */
1160                 btrfs_abort_transaction(trans, root, ret);
1161                 goto fail;
1162         }
1163
1164         record_root_in_trans(trans, root);
1165         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
1166         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
1167         btrfs_check_and_init_root_item(new_root_item);
1168
1169         root_flags = btrfs_root_flags(new_root_item);
1170         if (pending->readonly)
1171                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
1172         else
1173                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
1174         btrfs_set_root_flags(new_root_item, root_flags);
1175
1176         btrfs_set_root_generation_v2(new_root_item,
1177                         trans->transid);
1178         uuid_le_gen(&new_uuid);
1179         memcpy(new_root_item->uuid, new_uuid.b, BTRFS_UUID_SIZE);
1180         memcpy(new_root_item->parent_uuid, root->root_item.uuid,
1181                         BTRFS_UUID_SIZE);
1182         new_root_item->otime.sec = cpu_to_le64(cur_time.tv_sec);
1183         new_root_item->otime.nsec = cpu_to_le32(cur_time.tv_nsec);
1184         btrfs_set_root_otransid(new_root_item, trans->transid);
1185         memset(&new_root_item->stime, 0, sizeof(new_root_item->stime));
1186         memset(&new_root_item->rtime, 0, sizeof(new_root_item->rtime));
1187         btrfs_set_root_stransid(new_root_item, 0);
1188         btrfs_set_root_rtransid(new_root_item, 0);
1189
1190         old = btrfs_lock_root_node(root);
1191         ret = btrfs_cow_block(trans, root, old, NULL, 0, &old);
1192         if (ret) {
1193                 btrfs_tree_unlock(old);
1194                 free_extent_buffer(old);
1195                 btrfs_abort_transaction(trans, root, ret);
1196                 goto fail;
1197         }
1198
1199         btrfs_set_lock_blocking(old);
1200
1201         ret = btrfs_copy_root(trans, root, old, &tmp, objectid);
1202         /* clean up in any case */
1203         btrfs_tree_unlock(old);
1204         free_extent_buffer(old);
1205         if (ret) {
1206                 btrfs_abort_transaction(trans, root, ret);
1207                 goto fail;
1208         }
1209
1210         /* see comments in should_cow_block() */
1211         root->force_cow = 1;
1212         smp_wmb();
1213
1214         btrfs_set_root_node(new_root_item, tmp);
1215         /* record when the snapshot was created in key.offset */
1216         key.offset = trans->transid;
1217         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1218         btrfs_tree_unlock(tmp);
1219         free_extent_buffer(tmp);
1220         if (ret) {
1221                 btrfs_abort_transaction(trans, root, ret);
1222                 goto fail;
1223         }
1224
1225         /*
1226          * insert root back/forward references
1227          */
1228         ret = btrfs_add_root_ref(trans, tree_root, objectid,
1229                                  parent_root->root_key.objectid,
1230                                  btrfs_ino(parent_inode), index,
1231                                  dentry->d_name.name, dentry->d_name.len);
1232         if (ret) {
1233                 btrfs_abort_transaction(trans, root, ret);
1234                 goto fail;
1235         }
1236
1237         key.offset = (u64)-1;
1238         pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
1239         if (IS_ERR(pending->snap)) {
1240                 ret = PTR_ERR(pending->snap);
1241                 btrfs_abort_transaction(trans, root, ret);
1242                 goto fail;
1243         }
1244
1245         ret = btrfs_reloc_post_snapshot(trans, pending);
1246         if (ret) {
1247                 btrfs_abort_transaction(trans, root, ret);
1248                 goto fail;
1249         }
1250
1251         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1252         if (ret) {
1253                 btrfs_abort_transaction(trans, root, ret);
1254                 goto fail;
1255         }
1256
1257         ret = btrfs_insert_dir_item(trans, parent_root,
1258                                     dentry->d_name.name, dentry->d_name.len,
1259                                     parent_inode, &key,
1260                                     BTRFS_FT_DIR, index);
1261         /* We have check then name at the beginning, so it is impossible. */
1262         BUG_ON(ret == -EEXIST || ret == -EOVERFLOW);
1263         if (ret) {
1264                 btrfs_abort_transaction(trans, root, ret);
1265                 goto fail;
1266         }
1267
1268         btrfs_i_size_write(parent_inode, parent_inode->i_size +
1269                                          dentry->d_name.len * 2);
1270         parent_inode->i_mtime = parent_inode->i_ctime = CURRENT_TIME;
1271         ret = btrfs_update_inode_fallback(trans, parent_root, parent_inode);
1272         if (ret)
1273                 btrfs_abort_transaction(trans, root, ret);
1274 fail:
1275         pending->error = ret;
1276 dir_item_existed:
1277         trans->block_rsv = rsv;
1278         trans->bytes_reserved = 0;
1279 no_free_objectid:
1280         kfree(new_root_item);
1281 root_item_alloc_fail:
1282         btrfs_free_path(path);
1283         return ret;
1284 }
1285
1286 /*
1287  * create all the snapshots we've scheduled for creation
1288  */
1289 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
1290                                              struct btrfs_fs_info *fs_info)
1291 {
1292         struct btrfs_pending_snapshot *pending, *next;
1293         struct list_head *head = &trans->transaction->pending_snapshots;
1294         int ret = 0;
1295
1296         list_for_each_entry_safe(pending, next, head, list) {
1297                 list_del(&pending->list);
1298                 ret = create_pending_snapshot(trans, fs_info, pending);
1299                 if (ret)
1300                         break;
1301         }
1302         return ret;
1303 }
1304
1305 static void update_super_roots(struct btrfs_root *root)
1306 {
1307         struct btrfs_root_item *root_item;
1308         struct btrfs_super_block *super;
1309
1310         super = root->fs_info->super_copy;
1311
1312         root_item = &root->fs_info->chunk_root->root_item;
1313         super->chunk_root = root_item->bytenr;
1314         super->chunk_root_generation = root_item->generation;
1315         super->chunk_root_level = root_item->level;
1316
1317         root_item = &root->fs_info->tree_root->root_item;
1318         super->root = root_item->bytenr;
1319         super->generation = root_item->generation;
1320         super->root_level = root_item->level;
1321         if (btrfs_test_opt(root, SPACE_CACHE))
1322                 super->cache_generation = root_item->generation;
1323 }
1324
1325 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1326 {
1327         int ret = 0;
1328         spin_lock(&info->trans_lock);
1329         if (info->running_transaction)
1330                 ret = info->running_transaction->in_commit;
1331         spin_unlock(&info->trans_lock);
1332         return ret;
1333 }
1334
1335 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1336 {
1337         int ret = 0;
1338         spin_lock(&info->trans_lock);
1339         if (info->running_transaction)
1340                 ret = info->running_transaction->blocked;
1341         spin_unlock(&info->trans_lock);
1342         return ret;
1343 }
1344
1345 /*
1346  * wait for the current transaction commit to start and block subsequent
1347  * transaction joins
1348  */
1349 static void wait_current_trans_commit_start(struct btrfs_root *root,
1350                                             struct btrfs_transaction *trans)
1351 {
1352         wait_event(root->fs_info->transaction_blocked_wait, trans->in_commit);
1353 }
1354
1355 /*
1356  * wait for the current transaction to start and then become unblocked.
1357  * caller holds ref.
1358  */
1359 static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
1360                                          struct btrfs_transaction *trans)
1361 {
1362         wait_event(root->fs_info->transaction_wait,
1363                    trans->commit_done || (trans->in_commit && !trans->blocked));
1364 }
1365
1366 /*
1367  * commit transactions asynchronously. once btrfs_commit_transaction_async
1368  * returns, any subsequent transaction will not be allowed to join.
1369  */
1370 struct btrfs_async_commit {
1371         struct btrfs_trans_handle *newtrans;
1372         struct btrfs_root *root;
1373         struct work_struct work;
1374 };
1375
1376 static void do_async_commit(struct work_struct *work)
1377 {
1378         struct btrfs_async_commit *ac =
1379                 container_of(work, struct btrfs_async_commit, work);
1380
1381         /*
1382          * We've got freeze protection passed with the transaction.
1383          * Tell lockdep about it.
1384          */
1385         if (ac->newtrans->type < TRANS_JOIN_NOLOCK)
1386                 rwsem_acquire_read(
1387                      &ac->root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],
1388                      0, 1, _THIS_IP_);
1389
1390         current->journal_info = ac->newtrans;
1391
1392         btrfs_commit_transaction(ac->newtrans, ac->root);
1393         kfree(ac);
1394 }
1395
1396 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1397                                    struct btrfs_root *root,
1398                                    int wait_for_unblock)
1399 {
1400         struct btrfs_async_commit *ac;
1401         struct btrfs_transaction *cur_trans;
1402
1403         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1404         if (!ac)
1405                 return -ENOMEM;
1406
1407         INIT_WORK(&ac->work, do_async_commit);
1408         ac->root = root;
1409         ac->newtrans = btrfs_join_transaction(root);
1410         if (IS_ERR(ac->newtrans)) {
1411                 int err = PTR_ERR(ac->newtrans);
1412                 kfree(ac);
1413                 return err;
1414         }
1415
1416         /* take transaction reference */
1417         cur_trans = trans->transaction;
1418         atomic_inc(&cur_trans->use_count);
1419
1420         btrfs_end_transaction(trans, root);
1421
1422         /*
1423          * Tell lockdep we've released the freeze rwsem, since the
1424          * async commit thread will be the one to unlock it.
1425          */
1426         if (trans->type < TRANS_JOIN_NOLOCK)
1427                 rwsem_release(
1428                         &root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],
1429                         1, _THIS_IP_);
1430
1431         schedule_work(&ac->work);
1432
1433         /* wait for transaction to start and unblock */
1434         if (wait_for_unblock)
1435                 wait_current_trans_commit_start_and_unblock(root, cur_trans);
1436         else
1437                 wait_current_trans_commit_start(root, cur_trans);
1438
1439         if (current->journal_info == trans)
1440                 current->journal_info = NULL;
1441
1442         put_transaction(cur_trans);
1443         return 0;
1444 }
1445
1446
1447 static void cleanup_transaction(struct btrfs_trans_handle *trans,
1448                                 struct btrfs_root *root, int err)
1449 {
1450         struct btrfs_transaction *cur_trans = trans->transaction;
1451         DEFINE_WAIT(wait);
1452
1453         WARN_ON(trans->use_count > 1);
1454
1455         btrfs_abort_transaction(trans, root, err);
1456
1457         spin_lock(&root->fs_info->trans_lock);
1458
1459         if (list_empty(&cur_trans->list)) {
1460                 spin_unlock(&root->fs_info->trans_lock);
1461                 btrfs_end_transaction(trans, root);
1462                 return;
1463         }
1464
1465         list_del_init(&cur_trans->list);
1466         if (cur_trans == root->fs_info->running_transaction) {
1467                 root->fs_info->trans_no_join = 1;
1468                 spin_unlock(&root->fs_info->trans_lock);
1469                 wait_event(cur_trans->writer_wait,
1470                            atomic_read(&cur_trans->num_writers) == 1);
1471
1472                 spin_lock(&root->fs_info->trans_lock);
1473                 root->fs_info->running_transaction = NULL;
1474         }
1475         spin_unlock(&root->fs_info->trans_lock);
1476
1477         btrfs_cleanup_one_transaction(trans->transaction, root);
1478
1479         put_transaction(cur_trans);
1480         put_transaction(cur_trans);
1481
1482         trace_btrfs_transaction_commit(root);
1483
1484         btrfs_scrub_continue(root);
1485
1486         if (current->journal_info == trans)
1487                 current->journal_info = NULL;
1488
1489         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1490
1491         spin_lock(&root->fs_info->trans_lock);
1492         root->fs_info->trans_no_join = 0;
1493         spin_unlock(&root->fs_info->trans_lock);
1494 }
1495
1496 static int btrfs_flush_all_pending_stuffs(struct btrfs_trans_handle *trans,
1497                                           struct btrfs_root *root)
1498 {
1499         int flush_on_commit = btrfs_test_opt(root, FLUSHONCOMMIT);
1500         int snap_pending = 0;
1501         int ret;
1502
1503         if (!flush_on_commit) {
1504                 spin_lock(&root->fs_info->trans_lock);
1505                 if (!list_empty(&trans->transaction->pending_snapshots))
1506                         snap_pending = 1;
1507                 spin_unlock(&root->fs_info->trans_lock);
1508         }
1509
1510         if (flush_on_commit || snap_pending) {
1511                 ret = btrfs_start_delalloc_inodes(root, 1);
1512                 if (ret)
1513                         return ret;
1514                 btrfs_wait_ordered_extents(root, 1);
1515         }
1516
1517         ret = btrfs_run_delayed_items(trans, root);
1518         if (ret)
1519                 return ret;
1520
1521         /*
1522          * running the delayed items may have added new refs. account
1523          * them now so that they hinder processing of more delayed refs
1524          * as little as possible.
1525          */
1526         btrfs_delayed_refs_qgroup_accounting(trans, root->fs_info);
1527
1528         /*
1529          * rename don't use btrfs_join_transaction, so, once we
1530          * set the transaction to blocked above, we aren't going
1531          * to get any new ordered operations.  We can safely run
1532          * it here and no for sure that nothing new will be added
1533          * to the list
1534          */
1535         ret = btrfs_run_ordered_operations(trans, root, 1);
1536
1537         return ret;
1538 }
1539
1540 /*
1541  * btrfs_transaction state sequence:
1542  *    in_commit = 0, blocked = 0  (initial)
1543  *    in_commit = 1, blocked = 1
1544  *    blocked = 0
1545  *    commit_done = 1
1546  */
1547 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
1548                              struct btrfs_root *root)
1549 {
1550         unsigned long joined = 0;
1551         struct btrfs_transaction *cur_trans = trans->transaction;
1552         struct btrfs_transaction *prev_trans = NULL;
1553         DEFINE_WAIT(wait);
1554         int ret;
1555         int should_grow = 0;
1556         unsigned long now = get_seconds();
1557
1558         ret = btrfs_run_ordered_operations(trans, root, 0);
1559         if (ret) {
1560                 btrfs_abort_transaction(trans, root, ret);
1561                 btrfs_end_transaction(trans, root);
1562                 return ret;
1563         }
1564
1565         /* Stop the commit early if ->aborted is set */
1566         if (unlikely(ACCESS_ONCE(cur_trans->aborted))) {
1567                 ret = cur_trans->aborted;
1568                 btrfs_end_transaction(trans, root);
1569                 return ret;
1570         }
1571
1572         /* make a pass through all the delayed refs we have so far
1573          * any runnings procs may add more while we are here
1574          */
1575         ret = btrfs_run_delayed_refs(trans, root, 0);
1576         if (ret) {
1577                 btrfs_end_transaction(trans, root);
1578                 return ret;
1579         }
1580
1581         btrfs_trans_release_metadata(trans, root);
1582         trans->block_rsv = NULL;
1583         if (trans->qgroup_reserved) {
1584                 btrfs_qgroup_free(root, trans->qgroup_reserved);
1585                 trans->qgroup_reserved = 0;
1586         }
1587
1588         cur_trans = trans->transaction;
1589
1590         /*
1591          * set the flushing flag so procs in this transaction have to
1592          * start sending their work down.
1593          */
1594         cur_trans->delayed_refs.flushing = 1;
1595
1596         if (!list_empty(&trans->new_bgs))
1597                 btrfs_create_pending_block_groups(trans, root);
1598
1599         ret = btrfs_run_delayed_refs(trans, root, 0);
1600         if (ret) {
1601                 btrfs_end_transaction(trans, root);
1602                 return ret;
1603         }
1604
1605         spin_lock(&cur_trans->commit_lock);
1606         if (cur_trans->in_commit) {
1607                 spin_unlock(&cur_trans->commit_lock);
1608                 atomic_inc(&cur_trans->use_count);
1609                 ret = btrfs_end_transaction(trans, root);
1610
1611                 wait_for_commit(root, cur_trans);
1612
1613                 put_transaction(cur_trans);
1614
1615                 return ret;
1616         }
1617
1618         trans->transaction->in_commit = 1;
1619         trans->transaction->blocked = 1;
1620         spin_unlock(&cur_trans->commit_lock);
1621         wake_up(&root->fs_info->transaction_blocked_wait);
1622
1623         spin_lock(&root->fs_info->trans_lock);
1624         if (cur_trans->list.prev != &root->fs_info->trans_list) {
1625                 prev_trans = list_entry(cur_trans->list.prev,
1626                                         struct btrfs_transaction, list);
1627                 if (!prev_trans->commit_done) {
1628                         atomic_inc(&prev_trans->use_count);
1629                         spin_unlock(&root->fs_info->trans_lock);
1630
1631                         wait_for_commit(root, prev_trans);
1632
1633                         put_transaction(prev_trans);
1634                 } else {
1635                         spin_unlock(&root->fs_info->trans_lock);
1636                 }
1637         } else {
1638                 spin_unlock(&root->fs_info->trans_lock);
1639         }
1640
1641         if (!btrfs_test_opt(root, SSD) &&
1642             (now < cur_trans->start_time || now - cur_trans->start_time < 1))
1643                 should_grow = 1;
1644
1645         do {
1646                 joined = cur_trans->num_joined;
1647
1648                 WARN_ON(cur_trans != trans->transaction);
1649
1650                 ret = btrfs_flush_all_pending_stuffs(trans, root);
1651                 if (ret)
1652                         goto cleanup_transaction;
1653
1654                 prepare_to_wait(&cur_trans->writer_wait, &wait,
1655                                 TASK_UNINTERRUPTIBLE);
1656
1657                 if (atomic_read(&cur_trans->num_writers) > 1)
1658                         schedule_timeout(MAX_SCHEDULE_TIMEOUT);
1659                 else if (should_grow)
1660                         schedule_timeout(1);
1661
1662                 finish_wait(&cur_trans->writer_wait, &wait);
1663         } while (atomic_read(&cur_trans->num_writers) > 1 ||
1664                  (should_grow && cur_trans->num_joined != joined));
1665
1666         ret = btrfs_flush_all_pending_stuffs(trans, root);
1667         if (ret)
1668                 goto cleanup_transaction;
1669
1670         /*
1671          * Ok now we need to make sure to block out any other joins while we
1672          * commit the transaction.  We could have started a join before setting
1673          * no_join so make sure to wait for num_writers to == 1 again.
1674          */
1675         spin_lock(&root->fs_info->trans_lock);
1676         root->fs_info->trans_no_join = 1;
1677         spin_unlock(&root->fs_info->trans_lock);
1678         wait_event(cur_trans->writer_wait,
1679                    atomic_read(&cur_trans->num_writers) == 1);
1680
1681         /* ->aborted might be set after the previous check, so check it */
1682         if (unlikely(ACCESS_ONCE(cur_trans->aborted))) {
1683                 ret = cur_trans->aborted;
1684                 goto cleanup_transaction;
1685         }
1686         /*
1687          * the reloc mutex makes sure that we stop
1688          * the balancing code from coming in and moving
1689          * extents around in the middle of the commit
1690          */
1691         mutex_lock(&root->fs_info->reloc_mutex);
1692
1693         /*
1694          * We needn't worry about the delayed items because we will
1695          * deal with them in create_pending_snapshot(), which is the
1696          * core function of the snapshot creation.
1697          */
1698         ret = create_pending_snapshots(trans, root->fs_info);
1699         if (ret) {
1700                 mutex_unlock(&root->fs_info->reloc_mutex);
1701                 goto cleanup_transaction;
1702         }
1703
1704         /*
1705          * We insert the dir indexes of the snapshots and update the inode
1706          * of the snapshots' parents after the snapshot creation, so there
1707          * are some delayed items which are not dealt with. Now deal with
1708          * them.
1709          *
1710          * We needn't worry that this operation will corrupt the snapshots,
1711          * because all the tree which are snapshoted will be forced to COW
1712          * the nodes and leaves.
1713          */
1714         ret = btrfs_run_delayed_items(trans, root);
1715         if (ret) {
1716                 mutex_unlock(&root->fs_info->reloc_mutex);
1717                 goto cleanup_transaction;
1718         }
1719
1720         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1721         if (ret) {
1722                 mutex_unlock(&root->fs_info->reloc_mutex);
1723                 goto cleanup_transaction;
1724         }
1725
1726         /*
1727          * make sure none of the code above managed to slip in a
1728          * delayed item
1729          */
1730         btrfs_assert_delayed_root_empty(root);
1731
1732         WARN_ON(cur_trans != trans->transaction);
1733
1734         btrfs_scrub_pause(root);
1735         /* btrfs_commit_tree_roots is responsible for getting the
1736          * various roots consistent with each other.  Every pointer
1737          * in the tree of tree roots has to point to the most up to date
1738          * root for every subvolume and other tree.  So, we have to keep
1739          * the tree logging code from jumping in and changing any
1740          * of the trees.
1741          *
1742          * At this point in the commit, there can't be any tree-log
1743          * writers, but a little lower down we drop the trans mutex
1744          * and let new people in.  By holding the tree_log_mutex
1745          * from now until after the super is written, we avoid races
1746          * with the tree-log code.
1747          */
1748         mutex_lock(&root->fs_info->tree_log_mutex);
1749
1750         ret = commit_fs_roots(trans, root);
1751         if (ret) {
1752                 mutex_unlock(&root->fs_info->tree_log_mutex);
1753                 mutex_unlock(&root->fs_info->reloc_mutex);
1754                 goto cleanup_transaction;
1755         }
1756
1757         /* commit_fs_roots gets rid of all the tree log roots, it is now
1758          * safe to free the root of tree log roots
1759          */
1760         btrfs_free_log_root_tree(trans, root->fs_info);
1761
1762         ret = commit_cowonly_roots(trans, root);
1763         if (ret) {
1764                 mutex_unlock(&root->fs_info->tree_log_mutex);
1765                 mutex_unlock(&root->fs_info->reloc_mutex);
1766                 goto cleanup_transaction;
1767         }
1768
1769         /*
1770          * The tasks which save the space cache and inode cache may also
1771          * update ->aborted, check it.
1772          */
1773         if (unlikely(ACCESS_ONCE(cur_trans->aborted))) {
1774                 ret = cur_trans->aborted;
1775                 mutex_unlock(&root->fs_info->tree_log_mutex);
1776                 mutex_unlock(&root->fs_info->reloc_mutex);
1777                 goto cleanup_transaction;
1778         }
1779
1780         btrfs_prepare_extent_commit(trans, root);
1781
1782         cur_trans = root->fs_info->running_transaction;
1783
1784         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
1785                             root->fs_info->tree_root->node);
1786         switch_commit_root(root->fs_info->tree_root);
1787
1788         btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
1789                             root->fs_info->chunk_root->node);
1790         switch_commit_root(root->fs_info->chunk_root);
1791
1792         assert_qgroups_uptodate(trans);
1793         update_super_roots(root);
1794
1795         if (!root->fs_info->log_root_recovering) {
1796                 btrfs_set_super_log_root(root->fs_info->super_copy, 0);
1797                 btrfs_set_super_log_root_level(root->fs_info->super_copy, 0);
1798         }
1799
1800         memcpy(root->fs_info->super_for_commit, root->fs_info->super_copy,
1801                sizeof(*root->fs_info->super_copy));
1802
1803         trans->transaction->blocked = 0;
1804         spin_lock(&root->fs_info->trans_lock);
1805         root->fs_info->running_transaction = NULL;
1806         root->fs_info->trans_no_join = 0;
1807         spin_unlock(&root->fs_info->trans_lock);
1808         mutex_unlock(&root->fs_info->reloc_mutex);
1809
1810         wake_up(&root->fs_info->transaction_wait);
1811
1812         ret = btrfs_write_and_wait_transaction(trans, root);
1813         if (ret) {
1814                 btrfs_error(root->fs_info, ret,
1815                             "Error while writing out transaction");
1816                 mutex_unlock(&root->fs_info->tree_log_mutex);
1817                 goto cleanup_transaction;
1818         }
1819
1820         ret = write_ctree_super(trans, root, 0);
1821         if (ret) {
1822                 mutex_unlock(&root->fs_info->tree_log_mutex);
1823                 goto cleanup_transaction;
1824         }
1825
1826         /*
1827          * the super is written, we can safely allow the tree-loggers
1828          * to go about their business
1829          */
1830         mutex_unlock(&root->fs_info->tree_log_mutex);
1831
1832         btrfs_finish_extent_commit(trans, root);
1833
1834         cur_trans->commit_done = 1;
1835
1836         root->fs_info->last_trans_committed = cur_trans->transid;
1837
1838         wake_up(&cur_trans->commit_wait);
1839
1840         spin_lock(&root->fs_info->trans_lock);
1841         list_del_init(&cur_trans->list);
1842         spin_unlock(&root->fs_info->trans_lock);
1843
1844         put_transaction(cur_trans);
1845         put_transaction(cur_trans);
1846
1847         if (trans->type < TRANS_JOIN_NOLOCK)
1848                 sb_end_intwrite(root->fs_info->sb);
1849
1850         trace_btrfs_transaction_commit(root);
1851
1852         btrfs_scrub_continue(root);
1853
1854         if (current->journal_info == trans)
1855                 current->journal_info = NULL;
1856
1857         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1858
1859         if (current != root->fs_info->transaction_kthread)
1860                 btrfs_run_delayed_iputs(root);
1861
1862         return ret;
1863
1864 cleanup_transaction:
1865         btrfs_trans_release_metadata(trans, root);
1866         trans->block_rsv = NULL;
1867         if (trans->qgroup_reserved) {
1868                 btrfs_qgroup_free(root, trans->qgroup_reserved);
1869                 trans->qgroup_reserved = 0;
1870         }
1871         btrfs_warn(root->fs_info, "Skipping commit of aborted transaction.");
1872         if (current->journal_info == trans)
1873                 current->journal_info = NULL;
1874         cleanup_transaction(trans, root, ret);
1875
1876         return ret;
1877 }
1878
1879 /*
1880  * return < 0 if error
1881  * 0 if there are no more dead_roots at the time of call
1882  * 1 there are more to be processed, call me again
1883  *
1884  * The return value indicates there are certainly more snapshots to delete, but
1885  * if there comes a new one during processing, it may return 0. We don't mind,
1886  * because btrfs_commit_super will poke cleaner thread and it will process it a
1887  * few seconds later.
1888  */
1889 int btrfs_clean_one_deleted_snapshot(struct btrfs_root *root)
1890 {
1891         int ret;
1892         struct btrfs_fs_info *fs_info = root->fs_info;
1893
1894         if (fs_info->sb->s_flags & MS_RDONLY) {
1895                 pr_debug("btrfs: cleaner called for RO fs!\n");
1896                 return 0;
1897         }
1898
1899         spin_lock(&fs_info->trans_lock);
1900         if (list_empty(&fs_info->dead_roots)) {
1901                 spin_unlock(&fs_info->trans_lock);
1902                 return 0;
1903         }
1904         root = list_first_entry(&fs_info->dead_roots,
1905                         struct btrfs_root, root_list);
1906         list_del(&root->root_list);
1907         spin_unlock(&fs_info->trans_lock);
1908
1909         pr_debug("btrfs: cleaner removing %llu\n",
1910                         (unsigned long long)root->objectid);
1911
1912         btrfs_kill_all_delayed_nodes(root);
1913
1914         if (btrfs_header_backref_rev(root->node) <
1915                         BTRFS_MIXED_BACKREF_REV)
1916                 ret = btrfs_drop_snapshot(root, NULL, 0, 0);
1917         else
1918                 ret = btrfs_drop_snapshot(root, NULL, 1, 0);
1919         /*
1920          * If we encounter a transaction abort during snapshot cleaning, we
1921          * don't want to crash here
1922          */
1923         BUG_ON(ret < 0 && ret != -EAGAIN && ret != -EROFS);
1924         return 1;
1925 }